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Topic: Powering WS2812 LEDs (separate or from board?) (Read 2560 times) previous topic - next topic

terragady

Hi I am planning small lightning project with addressable leds. I have free two DC adaptors, 5V - 3A but very poor quality from china for 2$ and nice HP 12V - 2A. So should I connect 12V to the arduino and then from 5V to leds? Or 5V adapter to LEDs AND Board? I am not sure if I can connect such a adapter to 5V pin on arduino? Is there any risk? Maybe I should use DIODE there or some regulator? Or separate regulator 12V -> 5V and then 12V to the board and 5V to leds? :) Lot of combinations I know ;)
I want to run 1meter of 30LEDS (+/- few)

runaway_pancake

The Arduino 5V doesn't really have the juice to run 30X WS2812.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

terragady

so it doesn't matter what current is connected to VIN?
Should I just connect 5V adaptor to LEDs and 5V pin? Will it work? "Juice" will be from adaptor right?

runaway_pancake

The Arduino 5V has a limit to the current it can provide regardless of the capability of the main supply.
You posted that this 5V adapter of yours is of low quality ("very poor quality from china"), so I question running the Arduino from it.  Aside from that, what you propose is feasible.
(I hate to sign on to a proposal without a sketch/diagram.)
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

terragady

I do not want to have 2 adapters for on project, so is there any method I can improve this china thingy by adding something between it and 5V pin? Because the 5V should be nice and regulated already if I want to connect it there? I do not really know how to connect it any other way without buying additional power source or running arduino from battery. I will of course draw a sketch before :)

runaway_pancake

Define "very poor quality".  What is it lacking?  In what regard is it unacceptable?
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

terragady

well it cost nothing, smells like hell and I am not sure how stable is potential.

runaway_pancake

Then it's junk.  What next?

I think that you should probably buy what you need: a good 5V supply.  Do what's right, there is no magic bullet.

You could make a 5V supply from that 12V module; a regulator, a couple of capacitors and probably a heat-sink.  Here again - more stuff to buy.
As you're asking these questions, that may be outside your skill set.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

therion23

Hey folks. If i may chip in, i have a related question.

I am in a bit of the same situation, wanting to control N amounts of WS2832's, which way goes past what an Arduino of any kind can pass on. So, i'm thinking, giving those a separate power supply (5V 3A power supply) and letting the Arduino do the bitbanging to them.

Can this be done?

runaway_pancake

Can this be done?
Yes.  Please include a sketch of your proposal to confirm.
[2832's?]

The lengths or the number aren't the design criteria, exactly, but how many are let to be on at any time.
That's the crux of the matter - total current demand.
When specifics aren't discussed then worst case (the capacity for all ON, blazing white from each) has to be anticipated, my way of thinking.

A strip, or any number of strips, could be run from Arduino 5V, so long as the total is not greater than 30 elements, I suppose (but that might be a strain - no guarantees).

Powering the WS2812 strips from a 5V supply all their own takes all that load off the Arduino 5V, eliminating all of the calculations and considerations, the fuss and bother, and leaves you to get on with the fun stuff.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

PaulRB

You could make a 5V supply from that 12V module; a regulator, a couple of capacitors and probably a heat-sink.  Here again - more stuff to buy.
That would be very wasteful of power. A DC-DC convertor would be better.

runaway_pancake

"Waste"?  Stop already.
You got me, man.  I didn't cover every contingency, every possibility, every conceivable option.
Bad, Bad, Bad.  Bad.
All Replies must be exhaustive - I will keep this in mind.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

PaulRB

#12
Apr 25, 2016, 12:11 am Last Edit: Apr 25, 2016, 12:13 am by PaulRB
"Waste"?  Stop already.
You got me, man.  I didn't cover every contingency, every possibility, every conceivable option.
Bad, Bad, Bad.  Bad.
All Replies must be exhaustive - I will keep this in mind.

Don't get all defensive. I have huge respect for you. It's just a suggestion!

terragady

can i use something like this:
http://www.aliexpress.com/item/PWM-DC-6V-12V-24V-28V-3A-Motor-Speed-Control-Switch-Controller/32388647009.html?spm=2114.01010208.3.1.mMDTwd&ws_ab_test=searchweb201556_0,searchweb201602_5_10037_10033_507_10032_10020_10017_10021_10022_10009_10008_10018_101_10019,searchweb201603_9&btsid=4ec6973d-e9ef-4719-81e9-24712c45c00c

to convert 12V to 5V for leds? I tried it, used multimeter to adjust to 5V but the leds only turn on with different colours, few are off and they do not respond to arduino output pin, I can disconnect it and they will still be on

larryd

Show us a diagram of the wiring.
What voltage do you measure when operating the circuit?
Do you have a GND from the Arduino going to the power supply GND?

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